1. Field of Invention
This invention relates to an ophthalmic phototherapy device and an associated treatment method. More specifically, the present invention is related to a device and method for exposing an eye to selected wavelengths of light to promote the healing of damaged or diseased eye tissue.
2. Description of the Related Art
Light has various uses within the medical community. Exposure of cellular tissue to light is known to modulate the activity of such cellular tissue. Different wavelengths of light act on different mechanisms within individual cells within the cellular tissue to stimulate or suppress biological activity within the cells in a process commonly referred to as photobiomodulation. In certain photobiomodulation applications, commonly known as light therapy or phototherapy, the different wavelengths are used to promote healing, revitalize and rejuvenate cells, and in some circumstances, stimulate cellular regeneration and regrowth.
Molecules like cytochrome-C oxidase, hemoglobin, myoglobin, and nicotinamide adenine dinucleotide (NADH), found in cellular tissue, are recognized as photon acceptors and serve to initiate biochemical cellular response to photons. Additionally, it is recognized that certain biologic quantum field effects result from exposing cellular tissue to photonic light and that living cells generate low levels of photons, called biophotons. These biophotons are non-thermal in nature and are coupled to physiological functions in the cellular tissue. Biophotons represent regulatory activity from chemical reactivity within a cell and also perform regulatory activity over a given cellular tissue to promote cell growth and differentiation, and to provide intercellular and intracellular communication, such as for example, synchronicity in biofunction between cells. Such biophotons within a cellular tissue can be simulated by photonic light of one or more specific wavelengths from a source external to the cellular tissue. Such photonic light, when exposed to the cellular tissue, results in promotion of regulatory activity within the cells of the exposed cellular tissue.
Thus, it is generally accepted that cell activity can be up-regulated and down-regulated by specific wavelengths of low intensity light. The up- and down-regulation of cell activity through photobiomodulation is used to suppress cytokines, block the matrix metalloproteinases (MMP) cascade, suppress interleukins (IL) and tissue necrosis factors, and decreasing inflammation of cellular tissue. Photobiomodulation is also used to affect mitochondrial density and activity, cell proliferation and adhesiveness, and DNA and RNA production. Phototherapy has been shown to affect vascular endothelial growth factor (VEGF) expression (both enhancement and suppression) and to protect against a wide variety of toxins, such as chemical, ionizing, and bacteriologic toxins.
At least some of the known effects of the various wavelengths on body tissues are as follows. Light in the yellow range (approximately 577 nm to 597 nm) has been shown to switch off collagenase production by down-regulating MMPs and switching on new collagen production. Collagenases are enzymes that break down the native collagen that holds animal tissue together. Thus, use of light in the yellow range for phototherapy ultimately results in increased cohesion of cells in animal tissue. Light in the red range (approximately 640 nm to 700 nm) has been shown to decrease inflammation in injured tissue, increase ATP production, and otherwise stimulate beneficial cellular activity. Light in the blue range (approximately 405 nm to 450 nm) has been shown to kill various microorganisms. For example, light in the blue range has been shown to kill the propionibacterium that causes acne by activating the porphyrins produced by the bacteria. Accordingly, phototherapy has been utilized to treat infants for jaundice (e.g., U.S. Pat. No. 6,811,563), to treat acne and other skin conditions (e.g., U.S. Pat. No. 6,387,089), to treat rhinitis (e.g., U.S. Pat. No. 5,683,436), and to treat traumatic tissue injuries (e.g. U.S. Pat. No. 6,471,716).
Photobiomodulation also requires the use of light with suitable intensity, energy, and wavelengths, the combination of which allows light of the selected wavelengths to penetrate the cellular tissue and activate the desired cellular mechanism without significantly causing damage to the cells. The combination of characteristics suitable for photobiomodulation applications are distinct from those of light used in other applications. Other applications use high-energy, high-intensity light sources, e.g., excimer lasers, that are destructive as opposed to regenerative, because the light emitted is so intense that, as the laser light penetrates the cellular tissue, the cells become burned, melted, or otherwise destroyed. General purpose lighting, such as an incandescent light, uses low-energy light sources ranging in intensity that is incapable of sufficiently penetrating the cellular tissue, which results in superficial exposure of the cellular tissue to the low-energy light and, therefore, reduced photobiomodulation effects. Further, an incandescent light produces numerous wavelengths and the wavelengths are not subject to independent control, which results in unpredictable modulation of the cellular activity within the exposed cellular tissue. High-intensity light of sufficient energy to properly penetrate the cellular tissue and initiate photobiomodulation tends to burn and/or melt the cellular tissue prior to the completion of a phototherapy treatment. Hence, light appropriate for use in phototherapy should exhibit both a relatively low intensity, so as not to destroy the exposed cells, and a relatively high energy, so as to allow for sufficient penetration of light into the exposed cellular tissue such that the activities of a desired portion of cells within the exposed cellular tissue are photobiomodulated.
One device which is known to produce relatively low-intensity, high-energy light suitable for use in phototherapy is the light-emitting diode (LED). Several commercial phototherapy devices are available including devices which utilize LEDs, including the Gentlewaves® LED Photomodulation Device manufactured by Light BioScience, LLC, which includes a panel of LEDs for treating skin conditions, and the Flip4 Max7 LED device which incorporates an LED panel capable of producing multiple wavelengths of light, and which is also marketed for treating skin conditions. Further, the U.S. military and NASA have utilized small hand-held devices incorporating LED arrays that are used to reduce inflammation and to promote healing in damaged skin tissue. Light from such LED devices has been shown to exhibit the low-intensity and high-energy characteristics appropriate for use in photobiomodulation.
Various laser devices have been used in the field of ophthalmology for the purposes of ablating and cutting eye tissue during laser-assisted surgery on an eye. Likewise, various laser devices have been used to melt or otherwise liquefy eye tissue surrounding a surgical wound in order to establish a weld or other such seal in the surgical wound. These destructive uses of light cause other damage to the eye tissue, but this other damage is of the type that can be healed by the body's normal recuperative mechanisms over time. In addition, a device using LEDs has been utilized in the field of ophthalmology in an effort to strengthen corneal tissue. However, this device utilizes LEDs producing wavelengths falling in the middle to far ultraviolet ranges (approximately 100 nm to 300 nm) to induce cross-linking of corneal collagen and thereby stiffen the cornea of the eye. Thus, this process, in effect, ages the corneal tissue, as opposed to facilitating the production of new, “normal” tissue. Therefore, the process is not one in which healing of eye tissue is promoted. Accordingly, none of the known phototherapy mechanisms are used for promoting the healing, regrowth, or regeneration of damaged or diseased eye tissue or for alleviating discomfort associated with damaged or diseased eye tissue within the field of ophthalmology.